Method and apparatus for detecting and smoothing diagonal features in video images

ABSTRACT

A digital image processor includes an input buffer operable to receive an interlaced video stream and a digital memory for storing portions of the interlaced video stream. An output buffer is operable to transmit a deinterlaced video stream. Also included is a deinterlacing processor coupled between said input buffer and said output buffer and to said digital memory, said deinterlacing processor is operable to store portions of said received interlaced video stream from said input buffer into said digital memory and to detect diagonal features in said portions of said received interlaced video stream in said digital memory, and to generate said deinterlaced video stream having smoothed diagonal features therefrom.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Patent ProvisionalApplication No. 60/100,104 filed on Sep. 15, 1998, and is related toU.S. patent application Ser. No. 09/167,527 filed on Oct. 6, 1998 andU.S. patent application Ser. No. 09/372,715 filed Aug. 11, 1999, all ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to the processing ofvideo images and, more particularly, to techniques for detecting andsmoothing diagonal features in video images.

[0004] 2. Description of the Related Art

[0005] All major television standards use a raster scanning techniqueknown as “interlacing” or “interlace scanning.” Interlace scanning drawshorizontal scan lines from the top of the screen to the bottom of thescreen in two passes. Each pass is known as a field. In the NationalTelevision System Committee (NTSC) standard used in North America, eachfield takes approximately {fraction (1/60)}^(th) of a second to draw.

[0006] Interlace scanning depends of the ability of the cathode ray tube(CRT) phosphors to retain an image for a few milliseconds, in effectacting like a “memory” to retain the previous field while the newerinterleaved field is being scanned. Interlace scanning provides abenefit in television systems by doubling the vertical resolution of thesystem without increasing broadcast bandwidth.

[0007]FIG. 1 shows a number of parallel horizontal scan lines 10 on aconventional television display. A first set of horizontal lines 12 isscanned in a first field period and then a second set of horizontallines 14 is scanned in a second field period. Thus, the first field istemporarily shifted by {fraction (1/60)}^(th) of a second from thesecond field. When rapidly changing images are being displayed, anobject in motion may appear to be fuzzy due to the temporal displacementbetween the two fields.

[0008] This temporal displacement typically does not create a problem onconventional television displays, primarily because the image of the“older” field quickly fades in intensity as the light output of thephosphors decays. A secondary reason is that the spatial displacement inthe images caused by motion results in a fine detail that televisiondisplays resolve well. For these reasons, interlace scanning of motionpictures works acceptably well on conventional television displays.

[0009]FIG. 2 shows a set of progressively scanned horizontal lines 16.In progressive scanning, all horizontal lines 16, are scanned out in onevertical pass 18, so there is no time displacement of adjacent lines asin interlace scan. Progressive scanning requires a much higher bandwidthsignal. Consequently, progressive scanning is typically used forapplications where improved image quality and higher resolution arerequired, relative to conventional television systems. Progressivescanning is widely used in computer CRTs and liquid crystal displays(LCD).

[0010] Of a motion picture formatted for an interlaced monitor device asin FIG. 1 is to be displayed on a progressively scanned device as inFIG. 2, then it must be converted from the interlaced format to theprogressive format. This format conversion is known as deinterlacing.FIG. 3 is a flow diagram of a deinterlace process 19 of the prior art. Afirst series of interlaced video fields 20 is generated by a videosource (not illustrated) at {fraction (1/60)}^(th) second intervals.

[0011] In this example, each of the video fields 20 has a spatialresolution of 720 horizontal by 240 vertical pixels. Each field containshalf the vertical resolution of a complete video image. The first seriesof video fields 20 are input to a deinterlace processor 22, whichconverts the 720 by 240 interlaced format to a second series of videofields 24. In this example, each of the second series of video fields 24may have 720 by 480 pixels where the fields are displayed at 60 framesper second.

[0012]FIG. 4 shows a prior art method 25 of deinterlace processing. Avideo field 26 containing scan lines 30, and a previous video field 28containing scan lines 32 is fed into a field combination deinterlaceprocessor 34. The result is a combined frame 36 with scan lines 38sourced from video field 26 and scan lines 40 sourced from video field28. When this simple deinterlacing of the prior art is performed, and amotion picture formatted for an interlace display is converted to aprogressive format, a noticeable “artifact” or error arises because theimage content of vertically adjacent lines is time shifted by {fraction(1/60)}^(th) second as noted previously. The error is most visiblearound the edges of objects that are in motion.

[0013]FIG. 5 shows a deinterlaced image 42 with a stationary object 43that is rendered without distortion. FIG. 6 shows an image 44 with theobject 43′ in motion. The edges of object 43′ create artifacts 45 on theedges of the image 44 because of the aforementioned temporal shift.These artifacts 45 are introduced into the image by the conventionalfield combination deinterlacing method 25 of FIG. 4.

[0014]FIG. 7 is an illustration of an alternative prior art method 46 todeinterlace an image using a single reference field rather than twofields. The method 46 interpolates or doubles the number of lines of onefield to produce a progressive frame. A video field 48 is scanned froman image to contain a half set of lines 50. The half set of lines 50 isdeinterlaced by line interpolation in a deinterlacing interpolator 52.

[0015] The resulting frame 54 will have all the lines 50 of the originalvideo field 48. The remaining lines 56 are created by interpolation oflines 50. The resultant image will not have motion artifacts because allthe lines in the image will be created from lines 50 that are timecorrelated. This alternative method 46 of deinterlacing does not producemotion artifacts, but the vertical resolution of the image is reduced byhalf.

[0016] Reduction in vertical resolution is particularly noticeable inareas within the image that have high contrast diagonal features. Inthis case, the reduction in vertical resolution results in a jaggedappearance to diagonal image features. FIG. 8 illustrates a conventionaltwo-dimensional array of pixels 58 in which a high contrast diagonalfeature exists. This array 58 is the output of a deinterlace processor.The lines numbered 0, 2, 4, 6, and 8 come from one original video field,and lines 1, 3, 5, and 7 come from the previous original video field.

[0017] If a motion artifact is detected in the region of these pixels,then the deinterlace processor will discard the pixels from the previousfield in lines 1, 3, 5, and 7. The array 60 containing the remainingpixels in lines 0, 2, 4, 6, and 8 are shown in FIG. 9. The deinterlaceprocessor will then compute the missing pixels from the lines shown inFIG. 9 producing a very jagged image 62 as shown in FIG. 10.

[0018] In summary, prior art deinterlacing methods that operate basedupon interpolation reduce the vertical resolution of the original image.This reduction in resolution is particularly noticeable in images withhigh contrast diagonal features. In view of the foregoing, it isdesirable to have a method that detects diagonal features and smoothensthe jagged appearance caused by a reduction in resolution along diagonalfeatures in areas where deinterlace processing takes place.

SUMMARY OF THE INVENTION

[0019] The present invention fills these needs by providing an efficientand economical method and apparatus for detecting and smoothing highcontrast diagonal features in video images. It should be appreciatedthat the present invention can be implemented in numerous ways,including as a process, an apparatus, a system, a device or a method.Several inventive embodiments of the present invention are describedbelow.

[0020] In one embodiment of the present invention, a digital imageprocessor is provided. The digital image processor includes adeinterlacing processor coupled between an input buffer operable toreceive an interlaced video stream and an output operable to transmit adeinterlaced video stream. The deinterlacing processor is also coupledto a digital memory for storing portions of the interlaced video signal.The deinterlacing processor is operable to detect said diagonal featuresin the portions of the received interlaced video stream and to generatethe deinterlaced video stream having smoothed diagonal features.

[0021] In another embodiment of the present invention, a method fordeinterlacing an interlaced video stream is provided. The methodincludes receiving a video frame including a number of pixels from aninput of the interlaced video stream. The video frame is analyzed forfrequency information inherent to the video frame in order to detectmotion artifacts and the magnitude of the motion artifacts in the pixelsin the video frame. Diagonal features surrounding the pixels in thevideo frame are detected if a motion artifact is detected. Each pixel isthen mixed with a set of spatially corresponding pixels to generate anoutput pixel, while using the magnitude of the motion artifacts as acontrol, to generate an output pixel.

[0022] In another embodiment of the present invention, a method fordeinterlacing an interlaced video stream is provided. The methodincludes receiving a video frame including a number of pixels from aninput of the interlaced video stream. The video frame is analyzed forfrequency information inherent to the video frame in order to detectmotion artifacts. A number of motion artifact detection values isdetermined for the pixels in the video frame. A magnitude for theplurality of motion artifact detection values is then determined.Diagonal features surrounding the pixels in the video frame are detectedif a motion artifact is detected. Each pixel is then mixed with a set ofspatially corresponding pixels to generate an output pixel, while usingthe magnitude of the motion artifacts as a control, to generate anoutput pixel.

[0023] An advantage of the present invention is that it allows fordetection and smoothing of high contrast diagonal features that resultfrom deinterlacing video images. By reducing the effect of the diagonalfeatures, the processed video image becomes clearer and much lessjagged.

[0024] Other aspects and advantages of the invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings, illustrating by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be readily understood by the followingdetailed description in conjunction with the accompanying drawings. Tofacilitate this description, like reference numerals designate likestructural elements.

[0026]FIG. 1 shows a number of parallel horizontal scan lines on aconventional television display.

[0027]FIG. 2 shows a set of progressively scanned horizontal lines in aprior art progressive scan display.

[0028]FIG. 3 is an illustration of a deinterlace process of the priorart.

[0029]FIG. 4 is a further illustration of deinterlace processing of theprior art.

[0030]FIG. 5 shows a deinterlaced image of the prior art with astationary object.

[0031]FIG. 6 shows a deinterlaced image of the prior art with an objectin motion, creating undesirable “artifacts.”

[0032]FIG. 7 is a flow diagram of an alternative prior art method todeinterlace an image using a single reference field.

[0033]FIG. 8 illustrates a conventional two-dimensional array of pixelsin which a high contrast diagonal feature exists.

[0034]FIG. 9 illustrates an array used in a conventional interpolationdeinterlacing system containing half of the pixels in the array of FIG.8.

[0035]FIG. 10 illustrates an image produced by a prior art deinterlaceprocessor from video fields with high contrast diagonal features.

[0036]FIG. 11 shows a two-dimensional array of pixel values that is asubset of the combined frame of FIG. 4 that will be used in thedescription of the present invention.

[0037]FIG. 12 is a diagram showing a method to calculate detectionvalues in accordance with the present invention.

[0038]FIG. 13 is a block diagram of a mixing circuit of the presentinvention.

[0039]FIG. 14 is a diagram of an exemplary operation of the mixingcircuit when the DV is greater than “0”, but less than “1”.

[0040]FIG. 15 is an illustration of a method for detecting diagonalfeatures in accordance with the present invention.

[0041]FIG. 16 is a block diagram of a diagonal mixing circuit of thepresent invention.

[0042]FIG. 17 is a diagram showing the pixels of secondary array usedfor calculating the output of the diagonal mixing circuit of FIG. 16.

[0043]FIG. 18 is a flow chart of a diagonal detection method 570 inaccordance with one embodiment of the present invention.

[0044]FIG. 18 is a flow chart of a diagonal detection method inaccordance with the present invention.

[0045]FIG. 19 is a flow chart of a diagonal detection method, whichillustrates method of FIG. 18 in greater detail.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] A method and apparatus for diagonal enhancement of thedeinterlace process of a video image is disclosed. In the followingdescription, numerous specific details are set forth in order to providea thorough understanding of the present invention. It will beunderstood, however, to one skilled in the art, that the presentinvention may be practiced without some or all of these specificdetails. In other instances, well known process operations have not beendescribed in detail in order not to unnecessarily obscure the presentinvention.

[0047] FIGS. 1-10 were discussed with reference to the prior art. FIG. 4illustrated the combination of two temporally shifted fields that areadjacent in time, which are combined to create a frame that has doublethe vertical resolution of each field. For example, if the fields have aresolution of 720 horizontal pixels by 240 vertical pixels, then thecombined frame has a resolution of 720 horizontal pixels by 480 verticalpixels. This combined frame will have the full vertical resolutionavailable from the source, but is also prone to having motion artifacts.

[0048]FIG. 11 shows a two-dimensional array of pixel values 102 that isa subset of the combined frame 36 of FIG. 4. The array is part of theinterlaced video stream that is received by an input buffer. Thecombined frame 36 may be stored in a digital memory 103. Digital memory103 is used to store portions of the interlaced video stream, and isparticularly useful for storing temporally adjacent video fields in thepresent invention. After deinterlacing, an output buffer is used totransmit the deinterlaced video stream.

[0049] The array 102 is shown having a width of 5 pixels and a height of7 pixels. The array 102 is labeled across the top C0 to C4 indicatingcolumns and is labeled vertically along the left side from the top tobottom R0 to R6 indicating rows. The pixels contained in array 102 areused to compute a frequency detection value, and the array 102 is usedto detect diagonal features and finally to compute the resulting pixel.

[0050] The array 102 is positioned so that a set of even numbered rows104 contain pixels from the most recent or “current” field of theoriginal source, and a set of odd numbered rows 106 contain pixels fromthe previous field. The array 102 is then stepped across the combinedframe 36 (see FIG. 4) from left to right horizontally. Each step causesthe pixels in each of columns C1, C2, and C3 and C4 to shift to thecolumn to its immediate left. The pixels in column C0 shift out of thearray 102, and a new column of pixels shifts into column C4.

[0051] After the array 102 has been stepped across all the horizontalpositions of the combined frame 36, it is stepped down vertically by twopixels and returned to the left side of the field of the combined frame36. Therefore, even numbered rows 104 contain pixels from the mostrecent field and odd numbered lines 106 contain pixels from the previousfield. The process then repeats itself as array 102 is then steppedacross the combined frame 36 again from left to right horizontally. Ateach position in the two-dimensional array, a detection value (DV) iscalculated.

[0052]FIG. 12 is a diagram showing a method 200 to calculate detectionvalues in accordance with the present invention. The array 102 is usedto determine the presence of motion artifacts using a frequencydetection circuit 202. Interlace motion artifacts in the array 102 aredetected by the frequency detection circuit 202 resulting in thecomputation of a detection value (DV) 203.

[0053]FIG. 13 is a block diagram of a mixing circuit 204 of the presentinvention. The DV 203 is preferably used in the mixing circuit 204. Themixing circuit 204 computes a new value for the pixel at location R3C2of array 102. If no motion artifacts are detected, then the value of theDV 203 will be “0” and the mixing circuit 204 will output the originalpixel R3C2. If the value of the DV 203 is “1”, then the mixing circuit204 will output the average of the pixels above and below R3C2, so theoutput of the mixing circuit 204 is the average of R2C2 and R4C2.

[0054]FIG. 14 is a diagram of an exemplary operation of the mixingcircuit 204 when the DV 203 is greater than “0”, but less than “1”. Themixing circuit 204 uses information from the three-pixel array 206 byblending R3C2, and the average of R2C2 and R4C2 to form a new outputpixel 208 at location R3C2. The DV 203 may also be used as a control inthe methods for detecting diagonal features described below.

[0055]FIG. 15 is an illustration of a method 300 for detecting diagonalfeatures. A secondary array 310 that is a subset of array 102 is inputinto a diagonal detection circuit 320 which operates in parallel to thefrequency detection circuit 202 of FIG. 12. If no diagonal feature isdetected, then the diagonal detection circuit 320 produces no output.However, if a diagonal feature is detected, the diagonal detectioncircuit 320 produces two outputs: a single bit Sign signal 322 and amultiple bit SlopeFade signal 324. The specific method for calculatingthe Sign and SlopeFade signals 322 and 324 is shown in FIG. 18 and itscorresponding description.

[0056] The Sign signal 322 is used to determine which pair of pixels isdiagonally adjacent to R3C2. The SlopeFade signal 324 is a measurementof the magnitude of a diagonal feature. Magnitude is determined by theamount of contrast along the diagonal feature. High contrast, such as adiagonal white line across a black background, will result in thehighest values of the SlopeFade signal 324. A lower contrast results ina lower value for the SlopeFade signal 324.

[0057]FIG. 16 is a block diagram of a diagonal mixing circuit 500 of thepresent invention. The diagonal mixing circuit 500 includes amultiplexer 510, a first mixer 520, and a second mixer 530. Themultiplexer 510 relies on the Sign signal 322 to determine which pair ofdiagonally adjacent pixels are used. After a pair of diagonally adjacentpixels is chosen, the first mixer 520 blends the pixel values that arevertically adjacent to R3C2 with those that are diagonally adjacent toR3C2. The amount of blending is determined by the SlopeFade signal 324,which is proportional to the magnitude of the diagonal feature that isdetected.

[0058] The second mixer 530 is the final mixing stage and is identicalto the mixing circuit 204 shown in FIG. 13. The second mixer 530produces an output that is determined by input pixel R3C2 and the outputof the first mixer 520. The DV 203 is the control input for second mixer530. In summary, the new pixel value at R3C2 is computed from pixelvalues from the array 310. The control signals for determining the finalpixel value are the DetectionValue (DV) 203, the Sign signal 322 and theSlopeFade signal 324.

[0059]FIG. 17 is a diagram showing the pixels of secondary array 310used for calculating the output of the diagonal mixing circuit 500. Ifno diagonal features are detected within the secondary array 310, thenthe output of the mixing circuit is determined from the pixels along aline 540. If a diagonal feature is detected in circuit 320, the pixelsthat are diagonally adjacent to R3C2 along a line 550 or a line 560 areused to calculate the output pixel. The Sign signal 322 is used todetermine which line 550 or 560 is used.

[0060]FIG. 18 is a flow chart of a diagonal detection method 570 inaccordance with one embodiment of the present invention. Method 570begins at an act 572 in which a video frame is received by the digitalimage processor. Motion artifacts are detected in the video frame by anact 574 through frequency analysis of each pixel. If motion artifactsare not detected in the video frame, method 570 returns to act 572 uponwhich a new video frame is received, unless it is determined that thelast frame has been examined in an act 582. If motion artifacts aredetected in a pixel, then an act 576 determines if diagonal features arepresent in the area surrounding the pixel. If not, method 570 returns toact 572 again through act 582.

[0061] If diagonal features are detected, then the pixel is mixed with aset of spatially corresponding pixels as described above to smooth thediagonal feature in an act 578. The resulting mixed pixel is then usedto generate an output pixel in an act 580. Act 582 then determineswhether method 570 has reached the last video frame to be detected. Ifthe last frame has not been reached, method 570 returns to act 572. Ifthe last frame has been reached, then method 570 ends.

[0062]FIG. 19 is a flow chart of a diagonal detection method 600, whichillustrates method 570 in greater detail. The method 600 shows the flowof logical and mathematical acts used to compute the SlopeFade signal324 and the Sign signal 322 from the pixel array 310. The corner pixelsare divided into two horizontal pairs and two vertical pairs by an act605. The horizontal pairs are labeled hv2 and hv4 and the two verticalpairs are labeled vv2 and vv4. Differences are computed for each pair ofcorner pixel values by subtraction, producing a pair of horizontaldifferences and a pair of vertical differences.

[0063] In an act 610, the two horizontal and vertical differences aresummed to produce a horizontal and vertical difference vector for thearray 310. An act 620 computes the absolute value of the horizontal andvertical difference vectors. A thresholding value is used to adjust themagnitude of the SlopeFade output 324 in an act 630. The output of act630 is an unqualified SlopeFade signal (unQualSlopeFade) that is stillsubject to being “zeroed out” by the DiagDetect signal and theSlopeDisQual signal produced by parallel acts of the method 600.

[0064] The signs of the horizontal and vertical differences from act 605are recorded and stored in an act 650. The signs indicate whether theact 605 resulted in positive or negative numbers. Then, in an act 660looks for cases where the signs of the horizontal and verticaldifference acts are in opposition to each other. If such cases arefound, then SlopeDisQual is set to “1”. If the signs of the differenceacts are not in opposition, then SlopeDisQual is “0”.

[0065] In act 660, the diagonal detector looks for diagonal featuresthat are relatively large; in particular, the feature must be largerthan the nine-pixel array 310 used as the input to the diagonalprocessor. Image features that are smaller than the array 310 can causethe diagonal processing to incorrectly detect a diagonal feature. Thesesmall features can be detected by observing the signs and settingSlopeDisQual accordingly.

[0066] An act 670 compares the magnitude of the horizontal and verticalvectors computed in act 620 in to detect a diagonal feature. Then, theDiagDetect signal is produced in an act 680 using the horizontal andvertical vectors. The ratio of the difference of the horizontal andvertical vectors and the sum of the horizontal and vertical vectors isadjusted by a threshold value, diagDetThresh.

[0067] A final SlopeFade output is computed in an act 700 which uses twosingle bit inputs are used to qualify the SlopeFade output. The firstbit is a DiagonalDetect bit and the second bit is a SlopeDisQual bit.SlopeFade will be zero if DiagDetect is 0 or if SlopeDisQual is a 1,otherwise, SlopeFade will take the value of unQualSlopeFade. TheSlopeDisQual signal changes the SlopeFade signal to zero for cases wherethe slope of the diagonal feature can not be reliably calculated.Finally, the Sign signal 322 is computed in an act 710 using the signbits produced by the sums of the horizontal and vertical vectorsperformed in act 610. The Sign signal 322 is computed using this logicalact to determine the slope of the diagonal feature.

[0068] It will therefore be appreciated that the present inventionprovides a method and apparatus for smoothing of diagonal features invideo images. This is accomplished by providing a digital imageprocessor having a deinterlacing processor coupled between an inputbuffer operable to receive an interlaced video stream and an outputoperable to transmit a deinterlaced video stream. The deinterlacingprocessor is also coupled to a digital memory for storing portions ofthe interlaced video signal. The deinterlacing processor is operable todetect the diagonal features in the portions of the received interlacedvideo stream and to generate the deinterlaced video stream havingsmoothed diagonal features.

[0069] The digital image processor is used to perform frequency analysisto detect the presence of motion artifacts and the magnitude of suchmotion artifacts. Diagonal features in the pixels with motion artifactsare then detected. A set of spatially corresponding pixels is chosenbased on the diagonal feature detection information and then mixed withthe pixel. The pixel is then used to generate an output pixel whileusing the magnitude of the motion artifacts as a control. Thecombination of these techniques results in a low-artifact deinterlacedimage with smooth diagonal features.

[0070] Other embodiments of the invention will be apparent to thoseskilled in the art from consideration of the specification and practiceof the invention. Furthermore, certain terminology has been used for thepurposes of descriptive clarity, and not to limit the present invention.The embodiments and preferred features described above should beconsidered exemplary, with the invention being defined by the appendedclaims.

What is claimed is:
 1. A digital image processor comprising: an input buffer operable to receive an interlaced video stream; digital memory for storing portions of the interlaced video signal; an output buffer operable to transmit a deinterlaced video stream; and a deinterlacing processor coupled between said input buffer and said output buffer and to said digital memory, said deinterlacing processor operable to store portions of said received interlaced video stream from said input buffer into digital memory and to detect said diagonal features in said portions of said received interlaced video stream in said digital memory, and to generate said deinterlaced video stream having smoothed diagonal features therefrom.
 2. A digital image processor as recited in claim 1, wherein the deinterlacing processor is operable to perform frequency analysis upon the received interlaced video stream in order to generate the deinterlaced video stream having reduced motion artifacts.
 3. A digital image processor as recited in claim 2, wherein the frequency analysis results in the detection of motion artifacts and of a magnitude of the motion artifacts.
 4. A digital image processor as recited in claim 2, wherein the deinterlacing processor includes a diagonal detection circuit, which is operable to determine a slopefade signal, said slopefade signal having a value proportional to the magnitude of the detected diagonal feature.
 5. A digital image processor as recited in claim 4, wherein the diagonal detection circuit is operable to determine a sign signal, said sign signal providing information regarding the slope of the detected diagonal feature.
 6. A digital image processor as recited in claim 5, further comprising a diagonal mixing circuit including a multiplexer, which determines a pair of diagonally adjacent pixels to be mixed based on the sign signal.
 7. A digital image processor as recited in claim 6, wherein the diagonal mixing circuit further includes a first mixer operable to mix the pixel with vertically adjacent pixels from the set of spatially corresponding pixels.
 8. A method for deinterlacing an interlaced video stream comprising: receiving a video frame including a plurality of pixels from an input of said interlaced video stream; analyzing frequency information inherent to said video frame in order to detect motion artifacts and a magnitude of the motion artifacts in said plurality of pixels in said video frame; detecting diagonal features surrounding said plurality of pixels in said video frame if a motion artifact is detected; and mixing each of said plurality of pixels with a set of spatially corresponding pixels, while using said magnitude of said motion artifacts as a control, to generate an output pixel.
 9. A method for deinterlacing an interlaced video stream as recited in claim 8, wherein said analyzing frequency information and said detecting diagonal features are performed in parallel.
 10. A method for deinterlacing an interlaced video stream as recited in claim 8, further comprising determining a slopefade signal, said slopefade signal having a value proportional to the magnitude of the detected diagonal feature.
 11. A method for deinterlacing an interlaced video stream as recited in claim 10, further comprising determining a sign signal, said sign signal providing information regarding the slope of the detected diagonal feature.
 12. A digital image processor as recited in claim 11, further comprising qualifying the slopefade signal with a slopedisqual signal, said slopedisqual signal determining whether the diagonal feature has been reliably detected.
 13. A digital image processor as recited in claim 12, wherein the set of spatially corresponding pixels includes a first averaged pixel and a second averaged pixel.
 14. A digital image processor as recited in claim 12, wherein the first averaged pixel is the average of one of two pairs of diagonally corresponding pixels chosen based on the sign signal.
 15. A digital image processor as recited in claim 14, wherein the second averaged pixel is the average of two pixels that are vertically adjacent to each of the plurality of pixels.
 16. A digital image processor as recited in claim 15, further comprising mixing the first averaged pixel and the second averaged pixel, using the slopefade signal as a control.
 17. A method for deinterlacing an interlaced video stream comprising: receiving a video frame including a plurality of pixels from an input of said interlaced video stream; analyzing frequency information inherent to said video frame in order to detect motion artifacts in said video frame; determining a plurality of motion artifact detection values for said plurality of pixels in said video frame; determining a magnitude for said plurality of motion artifact detection values; detecting diagonal features surrounding said plurality of pixels in said video frame if a motion artifact is detected; and mixing each of said plurality of pixels with a set of spatially corresponding pixels, while using said magnitude of said motion artifacts as a control, to generate an output pixel.
 18. A method for deinterlacing an interlaced video stream as recited in claim 17, wherein said analyzing frequency information and said detecting diagonal features are performed in parallel.
 19. A method for deinterlacing an interlaced video stream as recited in claim 17, further comprising determining a slopefade signal, said slopefade signal having a value proportional to the magnitude of the detected diagonal feature.
 20. A method for deinterlacing an interlaced video stream as recited in claim 19, further comprising determining a sign signal, said sign signal providing information regarding the slope of the detected diagonal feature.
 21. A method for deinterlacing an interlaced video stream as recited in claim 20, further comprising qualifying the slopefade signal with a slopedisqual signal, said slopedisqual signal determining whether the diagonal feature has been reliably detected.
 22. A method for deinterlacing an interlaced video stream as recited in claim 21, wherein the set of spatially corresponding pixels includes a first averaged pixel and a second averaged pixel.
 23. A method for deinterlacing an interlaced video stream as recited in claim 21, wherein the first averaged pixel is the average of one of two pairs of diagonally corresponding pixels chosen based on the sign signal.
 24. A method for deinterlacing an interlaced video stream as recited in claim 23, wherein the second averaged pixel is the average of two pixels that are vertically adjacent to each of the plurality of pixels.
 25. A method for deinterlacing an interlaced video stream as recited in claim 24, further comprising mixing the first averaged pixel and the second averaged pixel, using the slopefade signal as a control. 